1. Field of the Invention
This invention concerns core material for steering wheels made of long fiber-reinforced resin used as the steering wheels for vehicles such as automobiles.
2. Description of the Related Art
Recently, a method of manufacturing structural members of excellent strength has been developed as described in British Patent Publication No. GB2004835A by winding, around a frame or the like, bundles of resin-impregnated fibers. These fibers are prepared by impregnating continuous fibers, such as glass fibers or carbon fibers, with a resin such as polyester resin. Steering wheels of reduced weight and excellent strength have been provided by making the core for steering wheels by this manufacturing method.
Various devices in the steering mechanisms of automobiles have been adopted for driver safety in recent years. For example, a collapsible steering mechanism for absorbing shocks upon collision of a car in which a tube or the like that absorbs energy while being collapsed upon collision may be disposed in a steering column.
There have also been made various steering wheel configurations for protecting driver's chest from hitting against the boss portion of the steering wheel, these configurations being based on the results of tests for shock load when the shape of the steering wheel is varied. A core 15 for a steering wheel of the T-shaped 3-spoke type, for example, as shown in FIGS. 8 and 9, which comprises a ring portion 12, a boss portion 13, as well as a first spoke portion 14a, a second spoke portion 14b and a third spoke portion 14c, extended in a T-like configuration has frequently been used. The diverging angle .theta. between the first spoke portion 14a and the third spoke portion 14c (hereinafter simply referred to as the diverging angle) is made greater than 170.degree..
The safeguarding of life in car accidents is a most important problem, and it is desired that operators do not suffer from injuries during even the most severe collision accidents.
Accordingly, various modifications have been made in core 15 for T-shaped 3-spoke type steering wheels in order to improve safety characteristics as described above.